Voltage rotation indicator mounting apparatus

ABSTRACT

A voltage rotation indicator for testing the phase sequence of live multi-phase electrical power is mounted within a housing. The housing is provided with structure for removably mounting the indicator on a meter box or can during voltage rotation testing. Contact plungers extend from the housing and contact meter jaw test points in the meter box during testing. Field personnel are thus not required to insert their hands into the meter box to attach test clips to the live circuit.

BACKGROUND OF INVENTION

1. Field of Invention: The present invention relates to testing ofelectrical power distribution systems.

2. Description of Prior Art: In electrical power distribution it isnecessary to test the phase sequence of multiphase electrical power,using voltage or field rotation indicator. To perform such a test, apower meter is removed from its meter box and measurements are made ofthe field rotation of live three-phase electric power. So far as isknown, the meters or indicators presently available have utilized clipsfor attachment of the indicator to meter jaws of the electrical linesbeing tested. This required that field personnel manually insert andattach the clips into the meter box in the presence of live electricalpower. Even with great care taken, the risk of electrical shock wasstill present.

SUMMARY OF INVENTION

Briefly, the present invention provides a new and useful improvement ina voltage rotation indicator for testing the phase sequence ofmulti-phase electrical power. As is conventional, the voltage rotationindicator contains a voltage rotator test circuit and test indicatorsfor testing the phase rotation of multi-phase electric power at meterjaws in a power meter box. According to the improvement of the presentinvention, a housing is provided for containing the test circuit and thetest indicators. Structure is provided for mounting the housing with thepower meter box, preferably at an opening formed when the power meter isremoved from the meter box for access to the meter jaws. The housing isfurther provided with contact plungers for electrical connection of thetest circuit with the meter jaws. The contact plungers are resilientlyurged into contact with the meter jaws when the housing is mounted onthe power meter box. Accordingly, field personnel need not place theirhands in the meter box when conducting phase rotation tests of livemulti-phase electrical power.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a voltage rotation indicator according tothe present invention and an electrical power meter box adjacent eachother.

FIG. 2 is an isometric view of a voltage rotation indicator to thepresent invention.

FIG. 3 is a front elevation view of a voltage rotation indicatoraccording to the present invention.

FIG. 4 is a side elevation view, taken partly in cross-section, of avoltage rotation indicator according to the present invention mounted onan electrical power meter box.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In the drawings, the letter A designates generally an apparatusaccording to the present invention for mounting a voltage rotationindicator V (FIG. 4), which has a voltage rotator test circuit C mountedon a printed circuit board P and a suitable number of indicator lights I(FIG. 1).

The voltage rotator test circuit C, printed circuit board P andindicators lights I are conventional, commercially available items. Asuitable example of such items are those sold as the model DR700 Unitestrotary field indicator under the trademark BEHA (with gear design) ofCh. BEHA GmbH Technische Neuentwicklunge of Glottertal, West Germany. Itshould be understood, however, that other commercially available itemsmay be equally as well used, if desired.

The apparatus A is used for testing the phase rotation of multi-phaseelectrical power at a meter box B. As is conventional, meter box B isprovided with an incoming conduit 10 and an outgoing external conduit 12for providing protective cover for plural electric conductors conveyingmulti-phase, typically three-phase, electrical power to an electricalload. Within the meter box B, the incoming individual electricalconductors are physically separated from each other so that the outerconductors conveying two of the phases of electrical power may beconnected by connector tabs 14 to an outer pair of meter jaws 16 on aninsulator bar 18. The center incoming conductor conveying the thirdphase of electrical power is mounted within an internal conduit 20 andconnected from behind to a center meter jaw 22 on the insulator bar 18.

Outgoing electrical power from a first two of the electrical powerphases is separately conveyed from an outer pair or meter jaws 24mounted on an insulator bar 26 through connector tabs 28 and therefromthrough conductors extending into the outgoing electrical conduit 12 tothe load. The third phase of outgoing electrical power is conducted intoa central meter jaw 30 on insulator bar 26 to a conductor in an internalconduit 32 to the outgoing electrical conduit 12 and therefrom to theload.

In normal service use, the three-phase electrical power being providedto the load is conveyed from the meter jaws 16 and 22 into an upper setof connecting plugs or terminals of a conventional electrical powermeter which fit within such jaws. The electrical power passes throughthe meter, where the rate of power usage is measured, and then passesfrom a lower set of conventional connector terminals of the power meterinto the meter jaws 24 and 30. The electrical power then passes throughconductors to the load. The power meter when in use is mounted with acircular mounting rim 34, formed on a cylindrical collar 36 defining anopening 38, in a front face 40 of the meter box B. Before connecting theload to the multi-phase electrical power, it is necessary to test thevoltage or phase rotation of the multi-phase electrical power to insurethat the phase rotation is proper to prevent damage to the load. Thevoltage rotation indicator V is used for this function before the powermeter is connected to the meter box B.

The apparatus A, which contains the voltage rotation indicator V (FIG,4), includes a housing H containing the indicator test rotator circuitC, its printed circuit board P and the indicator lights I. The indicatorlights I are visible through openings 42 (FIG. 4) formed in a rear wall44 (FIG. 1) of the housing H. The printed circuit board P is mounted ona lower wall 46 (FIG. 4) of the housing H and is contained within aspace within the housing H defined by side walls and 50 and a top wall52.

The housing H is closed at an end opposite the rear wall 42 by asemicircular face plate 54 (FIGS. 2 and 4). The face plate 54 may alsobe other than semicircular, for example taking the form of a segment ofa circle. The face plate 54 has an inner portion 56 conforming to aportion of the opening 38 in the front face 40 of the meter box B. Theinner portion 56 of the face plate 54 extends inwardly from an outerportion 58 of the face plate 54 and is insertable into the opening 38.The inner portion 56 of the face plate 54 further has an inwardlytapered shoulder surface 60 formed thereon. The tapered shoulder surface60 provides a camming action, when needed, to aid in attaching the faceplate 54 in the housing H to the mounting rim 34 of the meter box B.

The outer portion 58 of the face plate 54 has a rim 62 extendingoutwardly from the inner portion 56 for engagement with a front face 64of the mounting rim 34 of the meter box B. A hanger jaw 66 serves tohang or attach the face plate 54 and the housing H from the mounting rim34. The hanger jaw 66 is attached at a lower rear portion 68 by asuitable bolt or screw 70, which extends through a hanger jaw 66 intothe outer portion 58 of the face plate 54.

The hanger jaw 66 extends upwardly from its lower rear portion 68 to acentral body portion 72 which fits over and extends upwardly from therim 62 of the face plate 54. The hanger jaw 66 has an arm 74 inwardlyextending from the central portion 72 to a downwardly extending lip 76.The lip 76, arm 74 and central portion 72 of hanger jaw 66 define a slot78 formed to receive the mounting rim 34 of the meter box B. Preferably,the slot 78 has dimensions conforming to those of the rim 34, so thatthe rim 34 is snugly fitted in the slot 78 when the apparatus A ismounted on the meter box B.

The housing H has a plurality of electrical contact plungers 80 mountedtherewith for separately electrically connecting the test circuit C witheach of the meter jaws 16 and 22. The electrical contact plungers 80extend outwardly from connector nuts 82 mounted on the inner portion 56of the face plate 54. The electrical contact plungers 80 are mounted atpositions (FIG. 3) conforming to the spacing of the meter jaws 16 and 22on the insulator bar 18 in the meter box B.

The electrical contact plungers 80 extend through the inner portion 56of the face plate 54 into plunger container sleeves 84 mounted inopenings 86 formed in the face plate 54. The plunger container sleeves84 are connected to the connecting nuts 82 and thus to the face plate54. The plungers 80 extend through rear plates 88 at the rear of theplunger sleeve 84.

A bias spring 90 is mounted within each of the plunger sleeves 84between the rear plate 80 and a plunger disk 92. Each plunger disk 92 isfixedly mounted on its associated contact plunger 80, normally biasingsame outwardly to its furthest extent (FIG. 2). The bias springs 90 thusresiliently urge the contact plungers 80 outwardly. However, whenelectrical contact is made by the contact plunger 80 with a meter jaw,such as meter jaws 16 or 22 (FIG. 4), the bias springs 90 yield,permitting the contact plungers 80 to move rearwardly, as indicated byan arrow 94. When this occurs, the bias springs 90 continue toresiliently urge the contact plungers 80 into contact with the meterjaws, particularly when the housing H is mounted on the power meter boxB. Flexible electrical conductors 96 are mounted in electricalconnection with each of the contact plunger 80 within the housing H toelectrically connect the plungers 80 separately to the printed circuitboard P and the test circuit C thereon. Conductors 97 are provided toseparately connect the test circuit C to each of the indicator lights I.If desired, a probe socket 98 may be mounted in one of the walls of thehousing H and be electrically connected to one of the conductors 96 topermit testing of the voltage of the electrical power being delivered.

In the operation of the present invention, after incoming electricalpower has been wired to the meter box B and before the power meter isinstalled thereon, a test operator fits the slot 78 of the hanger jaw 66over the rim 34 on the meter box B at a position where the contactplungers 80 are aligned with the meter jaws 16 and 22 which have liveelectrical power thereon. Electrical current passes from the meter jawsthrough the contact plungers 80 and the conductors 96 to the rotationindicator test circuit C on the printed circuit board P.

It is to be noted that in attaching the apparatus A to the meter box B,it is unnecessary for the meter operator to insert a hand or conductorinto the meter box B, which contains live electrical power at the meterjaws on the insulator bar 18. This greatly reduces the risk ofaccidental contact with the live electrical power, also reducing thepossibility of electrical shock or injury to the operator.

After the voltage rotation indicator V has been mounted by the apparatusA to the meter box B, the operator may then check the indicator lights Ito check the phase sequence. A first indicator light 100 if energizedindicates that the phase is in proper forward rotation, while a secondindicator light 102 indicates that the phase sequence is in a reverserotation. Indicator lights 104, 106 and 108 indicate, respectively,whether a first (or A) phase, a second (or B) phase and a third (or C)phase of the multi-phase power connection are opened, by remainingunlit. This occurs while the remainder of the indicators I, includingthe indicator lights 100 and 102, are emitting light.

After the phase rotation has been tested with the indicator V, anoperator need merely lift the housing H upwardly, moving the rim 34 onthe meter box B out of the slot 78 on the hanger jaw 66, again withoutrequiring the operator to insert a hand or a connector into the meterbox B. Assuming that the voltage rotation tested satisfactorily, aconventional electrical power meter may then be attached to the mountingrim 34 of the meter box B, permitting the passage of electrical powertherethrough.

Having described the invention above, various modifications of thetechniques, procedures, material and equipment will be apparent to thosein the art. It is intended that all such variations within the scope andspirit of the appended claims be embraced thereby.

I claim:
 1. In a voltage rotation indicator having a voltage rotatortest circuit and test indicators for testing the phase rotation ofmulti-phase electric power at meter jaws in a power meter box, theimprovement comprising:housing means for containing said test circuitand said test indicators; means for mounting said housing means on thepower meter box; means with said housing for electrically connectingsaid test circuit with the meter jaws; and means for resiliently urgingsaid means for electrically connecting into contact with the meter jawswhen said housing means is mounted on the power meter box.
 2. Theinvention of claim 1, wherein the .[.power meter.]. .Iadd.indicator.Iaddend.is removably mounted to a mounting rim of the power meter boxto form an opening for access to the meter jaws, and wherein said meansfor mounting comprises:means for mounting said housing means on themounting rim of the power meter box.
 3. The invention of claim 2,wherein said means for mounting comprises:a face plate having saidhousing means mounted therewith; and means for attaching said face plateto the mounting rim of the power meter box.
 4. The invention of claim 3,wherein said means for attaching said .[.fact.]. .Iadd.face.Iaddend.plate comprises:means for hanging said face plate from themounting rim of the power meter box.
 5. The invention of claim 4,wherein said means for hanging comprises:a hanger jaw having a slotformed therein to receive the mounting rim of the power meter box. 6.The invention of claim 4, wherein said means for hanging comprises:ahanger jaw having a slot formed therein conforming to the mounting rimof the power meter box.
 7. The invention of claim 4, wherein:said meansfor hanging is mounted extending upwardly from aid face plate.
 8. Theinvention of claim 3, wherein:said face plate has an inner portionconforming to the opening in the power meter box and insertable therein.9. The invention of claim 8, wherein:said inner portion of said faceplate has a tapered shoulder formed thereon to .[.aid.]. .Iadd.said.Iaddend.in attaching of said face plate to the mounting rim of thepower meter box.
 10. The invention of claim 8, wherein:said face platehas an outer portion having a rim extending outwardly from said innerportion for engagement with a front face of the mounting rim of thepower meter box.
 11. The invention or claim 10, wherein said means forattaching comprises:a hangar jaw having a slot formed therein to receivethe mounting rim of the power meter box; said hanger jaw being mountedextending upwardly from said rim of said outer portion of said faceplate.
 12. The invention of claim 1, wherein:said housing means hasopenings formed therein for viewing of said test indicators.
 13. Theinvention of claim 1, wherein said means for electrically connectingcomprises:contact plunger means for fitting into the meter jaws.
 14. Theinvention of claim 13, wherein meter jaws are present in the meter boxfor each phase of the multi-phase electric power, and wherein said meansfor electrically connecting comprises:plural contact plunger means, eachadapted to individually fit into a separate one of the meter jaws. 15.The invention of claim 14, wherein said means for resiliently urgingcomprises:bias spring means for resiliently urging said contact plungermeans into the meter jaws. .Iadd.
 16. In a voltage rotation indicatorhaving a voltage rotator test circuit and test indicators for testingphase rotation of multi-phase electric power at meter jaws in a powermeter box, the improvement comprising:housing means having an interiorspace for containing said test circuit; means for mounting the housingmeans on the power meter box; electrical contact plungers in electricalcontact with the test circuit, a portion of each of the plungersextending outwardly from the housing and spaced apart at distancescorresponding to distances between meter jaws, so that when the housingmeans is mounted on the power meter box, the outwardly extending plungerportions are in electrical contact with the meter jaws; and means forresiliently urging at least one of said electrical contact plungers intocontact with the meter jaws when said housing means is mounted on thepower meter box. .Iaddend. .Iadd.
 17. The invention of claim 16 whereinthe means for mounting comprises:means for mounting said housing meanson a rim surrounding an opening in a front face of the power meter box..Iaddend. .Iadd.18. The invention of claim 16 wherein the means formounting comprises: a face plate having said housing means mountedtherewith; and means for hanging said face plate onto the rim of thepower meter box. .Iaddend. .Iadd.19. The invention of claim 18 whereinthe means for hanging comprises a hanger jaw with a slot formed thereinto receive the rim of the power meter box. .Iaddend. .Iadd.20. In avoltage rotation indicator test circuit and test indicators for testingthe phase rotation of multi-phase electric power at meter jawsaccessible at an opening adjacent a mounting rim in a power meter box towhich a power meter is normally connected, the improvementcomprising:housing means for containing said test circuit and said testindicators; means for mounting said housing means on the mounting rim ofthe power meter box; and means with said housing for electricallyconnecting said test circuit with the meter jaws when the housing meansis mounted on the power meter box, wherein said means for mountingcomprises: a face plate having said housing means mounted therewith,said face plate having an inner portion conforming to the opening in thepower meter box and insertable therein; and means for attaching saidface plate to the mounting rim of the meter box. .Iaddend. .Iadd.21. Theinvention of claim 20 wherein:said inner portion of said face plate hasa tapered shoulder formed thereon to aid in attaching of said face plateto the mounting rim of the power meter box. .Iaddend.